Selection on tropane alkaloids in native and non‐native populations of Datura stramonium

Abstract

Theories of plant invasion based on enemy release in a new range assume that selection exerted by specialist herbivores on defence traits should be reduced, absent, or even selected against in the new environment. Here, we measured phenotypic selection on atropine and scopolamine concentration of Datura stramonium in eight native (Mexico) and 14 non‐native (Spain) populations. Native populations produced between 20 and 40 times more alkaloid than non‐native populations (atropine: 2.0171 vs. 0.0458 mg/g; scopolamine: 1.004 vs. 0.0488 mg/g, respectively). Selection on alkaloids was negative for atropine and positive for scopolamine concentration in both ranges. However, the effect sizes of selection gradients were only significant in the native range. Our results support the assumption that the reduction of plant defence in the absence of the plant's natural enemies in invasive ranges is driven by natural selection.

The complete chloroplast genomes of two Mexican plants of the annual herb Datura stramonium (Solanaceae)

“…The annual herb, Datura stramonium , is a member of the Solanaceae family (Castillo et al. 2019 ). This herb produces the highest concentration of tropane alkaloids within this family (Castillo et al.…”

Novel chemicals engender myriad invasion mechanisms

“…This article is protected by copyright. All rights reserved variation in soil nutrients (Effah et al, 2020) Chromolaena odorata Odoratin Higher amounts of odoratin in non- (Tharayil et al, 2009) Datura stramonium (native Atropine and scopolamine Greater amounts of two compounds in to Mexico; invasive in Spain) native range than in non-native range owing to presence of specialist herbivores (Castillo et al, 2019) Echium plantagineum Naphthoquinones and Defend against insect and (native to Europe and Asia; pyrrolizidine alkaloids livestock herbivory, competitive invasive in Australia) advantages against weeds (Skoneczny et al, 2019).…”

“…(b) Mycorrhizal colonisation and quercetin in root exudates of 60‐d‐old and 90‐d‐old Triadica sebifera plants from its native (China) and non‐native (USA) populations. (c) Average concentration of two defence chemicals, atropine (upper panel) or scopolamine (lower panel), produced by Datura stramonium in its native (Mexico) and non‐native (Spain) populations (Castillo et al ., 2019). Production of these two defence chemicals by D .…”

“…Ruckli et al (2014) identified a quinone (2-methoxy-1,4-naphthoquinone; 2-MNQ) from its root exudates and leaf leachates and argued that this chemical plays an important role in its invasive success. In one experiment, Gruntman et al (2016) tested whether the co-occurring species, Urtica or scopolamine (lower panel), produced by Datura stramonium in its native (Mexico) and non-native (Spain) populations (Castillo et al, 2019). Production of these two defence chemicals by D. stramonium was higher in the native range than its introduced range.…”

“…2c, lower panel), was 40 and 20 times greater, respectively, in Mexico, the native range of Datura stramonium (Solanaceae, jimson weed), than in Spain, its non‐native range (Castillo et al ., 2019). The greater production of these two chemicals in the native range was related to the presence of specialist enemies (Castillo et al ., 2019; Table 1). Therefore, NIS may produce greater quantities of novel chemicals involved in competition with other plants, but production of chemicals that defend against specialist enemies may decline in their non‐native ranges.…”